THE CHIMPANZEES AND ORANGS. 9 



Plate' ; it more resembles that of Man, The groove dividing it from the articular 

 convexity is very deep. 



In the Chimpanzee (PI. V. figs. 4-7), the ulna equals the humerus in length, and 

 both its backward (fig. 4) and double lateral (fig. 7) curves are more marked than in 

 the Gorilla. In both these respects the bone departs further from the human type. In 

 other respects it closely accords with the ulna of the Gorilla, except that the pits, 

 ridges, and prominences for muscular attachment are less strongly marked. The 

 breadth of the olecranon (fig. 7), in proportion to the length of that process, is less 

 than in the Gorilla, and somewhat greater than in Man. 



The chief distinctions presented, in this comparison, by the Human ulna are, — its 

 minor length compared with the humerus ; its greater relative slenderness ; the less 

 proportional expansion of the proximal end ; the somewhat minor production of the 

 coronoid process ; and the greater straightness of the shaft, especially on the side view 

 (comp. fig. 8 with figs. 1 & 4). 



The difference in the size and strength of the bone between the male European and 

 male Australian is exemplified in figures 8-10 and 12, 13, in PI. V. 



The skeleton of the old male Gorilla in the British Museum (PI. XI.) exemplifies a 

 consequence of the fracture of the humerus, in an interesting way and degree. Interstitial 

 absorption has operated upon the whole extent of the uninjured long bones of the limb, 

 viz. the radius and ulna, so as to slightly alter the shape of the ulna and reduce the 

 length of both bones, thus accommodating to a certain degree the length of the second 

 segment of the arm to the diminished strength and disadvantageous condition of the 

 first segment. The left radius is shorter by one-eleventh, than the right. This, with 

 the marks of disease in the fractured humerus, indicates the animal to have been able to 

 obtain its sustenance for some time after its climbing powers were injuriously affected 

 by the broken arm, and so far corroborates Mr. du Chaillu's account- of the terrestrial 

 habits of the male Gorilla, and the great proportion of the food which it obtains from 

 the ground. 



Bones of the Hand. — Plates II. & X. 

 Carpal bones. — Plate II. figs. 5-22. 



The bones of the wrist agree in number and relative position with those of Man ; but 

 the differences of shape and proportion give a greater breadth to the carpal segment, in 

 proportion to its length, in the Gorilla. The radial surface is nearly circular in 

 shape, instead of being oval and oblong as in Man. 



The OS scaphoides (PI. X. fig. I, s) presents a rather more prominent and regular 

 convexity (PI. II. fig. .5, c) for the radius ; and a greater production and expansion 



' T!ie distal epiphysis of the ulna, like that of the radius, was wanting in the only subject at my command, 

 for the illustration of my Paper, in 18.51. 



- Explorations in Equatorial Africa, 8to. 1861, pp. 275, 290. 



VOL. V. PART I. ^ 



